Polyester laminating resin, also known as fiberglass resin, is the most commonly used resin in the industry. It is used in a wide variety of projects including boats, car bodies, kayaks, surfboards, patio decks and aircraft. It is affordable and easy to use. It has a quick cure and adds dimensional stability. Polyester resin requires MEKP hardener.

Needed Supplies (this will vary depending on your project):

  • MEKP (methyl ethyl ketone peroxide) is required
  • Brushes/rollers/spreaders
  • Safety clothing- gloves, mask, eye protection
  • Mixing cups
  • Stir sticks or drill head
  • Cleaning supplies- rags, acetone etc.

-Work in a well-ventilated area. Polyester resin gives off strong fumes

-Wear proper safety clothing including gloves and a face mask

-Make sure the resin, room and the surface you are working on are heated up to room temperature.  The ideal temperature to work in is between 70-85 degrees.

-Use mixing cups to measure the resin

-MEKP can be used between 1% and 2% by volume of resin but we recommend 1.25% to 1.75% depending on how long of a pot life and working time is desired. The more MEKP that is used, the shorter the pot life/ working time will be. The less MEKP that is used, the more pot life/ working time there will be.

-Mix thoroughly for at least one minute.

-Apply immediately

-Depending on your project, you can use brushes, rollers, spreaders or squeegees to apply the resin.

-Work in smaller batches

-Gel time will vary from around 10-20 minutes depending on how much MEKP hardener was added and the room temperature

-Polyester resin has a shelf life of around 6 months.  Store in a cool dry space.

-Polyester resin without wax cures with a surface tack which helps multiple layers to adhere to each other. It also does not require sanding between layers.  A finish resin contains wax that creates a hard tack free finish. If you do not want to purchase a finish resin you can add surface seal to the laminating resin for the final layer of your project.

-Polyester resin can be used on wood, metal and fiberglass. Do not use polyester resin on styrofoam as it will melt it.

-Do not add too much MEKP.  If too much hardener is added, the finished product can be prone to fractures or resin will become rubbery in the mixing cup.

-If you do not add enough MEKP, your laminate may never cure.

***Always try out a small test batch first.  Working with resin is more of an art than a science***

By Dallin Leach 3 comment


comments (3)

  • Fiberglass Warehouse

    @Igor The time can be infinite. You just have to go back and sand before adding the next layer.

  • Igor

    Can you add additional layers without sanding after one week? In other words, what is the maxsimum time between layers?

  • peyman

    hello sir
    please help me about below :
    1- can mix silica powder as filler in polyester resin ?
    2-i want to use a gel coat for surface our products, can spry gel coat and after curing gel coat then add my mixture in the mold? this 2 layers ” gel coat and second layer ” will bonded to each other?

    REPLY from fgwarehouse: 1 – Yes, you can add fumed silica to polyester resin.
    2. I’m not quite understanding the question. The 1st and 2nd layers will bond together if you haven’t mixed wax into the 1st layer.

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